Magnetohydrodynamic buoyancy driven Al2O3-water nanofluid flow in a differentially heated trapezoidal enclosure with a cylindrical barrier

Abstract

This paper aims to analyse the influence of externally applied magnetic field on the free convection motion of Al2O3-water nanofluid in a partially heated trapezoidal enclosure with an internal cylindrical barrier. The thermal conductivity and viscosity of the nanofluid are estimated using the KKL (Koo-Kleinstreuer-Li) model. The thermal management of the water-based nanofluid in the enclosure is maintained by defining three different thermal conditions on the cylindrical barrier. The finite volume method (FVM) is adopted to solve the non-dimensional steady-state continuity, momentum and energy conservation equations. The study evaluates the effects of Rayleigh number (103 ≤ Ra ≤ 107), magnetic field strength (0 ≤ Ha ≤ 60), cavity inclination angle (0 ° ≤ ψ ≤ 60°), applied magnetic field angle (0 ° ≤ ϕ ≤ 90°), and enclosure aspect ratio (AR = 0.5, 0.75 and 1) on the thermohydraulic characteristics of nanofluid. The augmentation in the heat transfer rate in the enclosure is minimally affected by the volume fraction of nanoparticle. The angle of the applied external magnetic field greatly alters the flow and temperature distribution in the enclosure. The location of the minimum local Nusselt number shifts away from the middle of the bottom surface with increasing Hartmann number. Furthermore, the maximum non-dimensional velocity reduces with the increase in Hartmann number.